Uniting dissimilar metals



Patent @ct. ll, 19271 QOFFI a. Y

HARRY c. mooonx, or DAYTON, 01110, nssrenon TO GENERAL morons nnsnnncn CORPORATION, .OF DAYTON, OHIO,

A CORPORATION OF DELAWARE.

UNITING IDISSIMILAR METALS.

Ho Drawing. Application flledlanuary 2 This invention relates to the bonding of dissimilar metals such as copper and iron, and especially to the bondlng of cooling. fins to an engine cylinder.

The present invention is susceptible of a variety of uses and is particularly useful in connection with the cylinder finmng process described and claimed in the copending application of Charles F. Kettering, Serial h No. 514,014, filed November 9, 1921. This application describes the bonding to an'iron or steel engine cylinder of a continuous strip of copper fin material including a plurality of fin loops by means of an interme- 1 diate bonding e ement of sheet brass whichunites with the cylinder wall and withthe cop er fin material in suclia manner 'as to 7 pro uce a bond having mechanical perm-anence and providing true thermal contact 2 between the cylinder and the fins. The process described in the application referred to includes wrappin flexible fin 'material about the exterior cylindrical surface of the cylinder with a thin sheet of flexible brass between the cylinder and the ortions of the fin material to be united wit the cylinder, the surfaces to be united having been coated with a suitable flux. These arts are-temporarily held. in assemble relation, by means of binding wires the assembly is.

dipped in a bath to pro ide a protectingcoating for the fins, and'is then heated to a temperature su'flicient tomelt'the brass to cause it to unite with the iron and copper.

Especiallywhere a flexible copper body is to be united with a cylindricalferrous sur-" face it is advantageous to use a brass which can be obtained in thin flexible sheets, and one which has a relatively low melting point. It has been found that increasing the percentage of zinc and decreasing the percentage of copper in the Mass will cause the, melting point to be reduced, and. if the percentage of zinc is not too great, the bond when iormed will be sufiiciently tough to withstand the difierential expansion of the copper and iron and also mechanical shocks.

However, before the zinc content of sheet brass is increased to the point where a brittle bond would ,result, brass itself becomes brittle, and it is impossible to roll it into the jthin flexible sheets which can be wrapped around the cylinder. It has been .found that brass analyzing fifty percent zinc and fifty percent-copper brass having it to be worked into thin flexible It has been .found'that such a brass 1923. Serial No. 610,373.

will provide a tough bond, but it is imposper andthirty five percent zinc appears to ave the maximum zinc content consistentwith working it into thin flexible sheets. Obviously the last specified, brass has a higher melting point than the brass analyz-.

ing fifty ercent' copper fifty percent zinc. One obibet of the pre sent invention is to treats. bonding material'having the necessary thinness and flexibility v in such a way that certain metallic bodies'having reverse int'erfitti'ng nonplaniform surfaces can-be joined upon heating these metals with the treated bonding material between them to a temperature substantially less than possible when using the untreated bonding material, while yet forming a mechanically permanent joint. "This invention contemplates startingwith ametallic substance which can be obtained readily in thin flexible sheets, and in using this. flexible materialas a base to which can be attached oragainst which may be placedanother me tallic substance capable of alloying with the substance of the flexible sheet at a temperature lowerthan the melting point of the flexible sheet'when used alone as a bonding agent between metallic bodies having nonplaniform surfaces to be joined. The alloy mg temperature of the flexible sheet with the additional substance is also suflicient to cause the resulting alloy to become active with respect to the metals to be joined and to produce a strong tough bond when the alloy is'solid.

In appl used for one may start with a the ighest zinc content which will'permit sheets.

ping this process to brass to be razin analyzesabout sixty five percent copper and thirtyfive ercent zinc as stated be ore. A sheet of'this brass is coated with zinc, platin forexam 1c in a cyanide zinc bath until t e treated onding material analyzes a relatively much higher percentage of zinc, such asfiity percent zinc and fifty percent copper, or whatever is desirable do ending on the nature of the joint. Thefi .-fi

analysis has been found suitable for bonmg to an iron engine cylinder. The surfaces to be joined, such as the surfaces oi fin material and engine cylinder are fluxed; the fin material and bonding material are assembled around cylinder and secured thereto by binding wires; this assembly is 'coated with a protecting flux andis temperatures .to which the cylin er ma sub ected in use. The temperature at w 10hheated :to melt the bonding material to cause 'it to unite with the fin material. and cylinzinccoating and the brass sheet will alloy is lower than the meltingtemperature of a similar brass sheet 'u'ncoated. This alloying temperature is 'suflicient to cause the bonding material thus formed to be active with respect to the metals to be joined, that is, there is such an intermingling of this new allo with the metals to be joined that a mechanically ermanent joint is obtained. Therefore the sesiredresult is obtained with the use of less heat than necessary where theuncoatedflexible sheet is used.

It has been found that the alloying temperature for zinc coating and the exible' brass is higher than that of the meltinf'pomt of zinc, the alloying temperature. r the zinc coated brass sheet in the example given being about 1600 Fahr.

sixty five per cent zinc and thirty five per cent copper, since the strength of the joint.

need not be as reat between the co per located upon the Eat cylinder head as etween the copper fins and cylindrical surface of the cylinder.

Instead of using zinc coated flexible brass,

the flexible brass can be sandwiched between layers of sheet zinc and simply held in place by the binding wires which temporarily hold together the metals to be joined.

a It is preferable to use the zinc in two lay ers or coatings, one on each side of the flexible brass sheet' rather than to have. a thick layerof zinc between two layers of flexible brass. j

Instead of a flexible impervious sheet, the

brass may be in the form of a sheet offine flexible wire gauze which can serveas a base for a filling of zinc in the spacesbetween the wires.

In bonding with brass which includes a flexible core of brass and a coating of zinc,

it is desirable to have some of the total zinc content of the bonding material originally combined with the copper in order that the zinc will not run away before the temperature of the alloying of the brass with the zinc coating is reached. Therefore it is best to start with a brass having as high a zinc content as possible consistent with working it into flexible sheets. i

While the forms of embodiment of the invention as"herein disclosed, constitute preferred forms, it is to be understood that other forms might be adopted, all coming within sheet and associated ingredient and thereby the union of the bodies; the two ingredients of the desired bonding alloy being of such character and such proportions that if alloyed in asingle sheet, said sheet would be too inflexible .to be forced into conformity Where it is desired to bond a copper equal-- izer upon the head of a cylinder, the flexible brass sheet can be coated with zinc to analyze with said surfaces.

2. The process of uniting copper and ferrous bodies having reverse non-planiform surfaces, which includes placing between saidsurfaces a sheet of brass with zinc uniformly distributed with respect to the sheet of brass, heating the assembly to a -temperature suflicient to cause the zinc and brass to alloy and thus bond the bodies together.

3. The process-of uniting a flexible copper body to the curved surface of a ferrous body, which comprises placing between the two bodies a flexible brass sheet coated with zinc and heating the brass and zinc sufficiently to cause them to alloy and thus bond the two bodies together. 4. The proceis of uniting a flexible copper body to the curved surface of a ferrous. body, which comprises placing between the two bodies a flexible brass sheet associated with a nature. 4 I

HARRY'G. MOUGEY. 

